The Schedule Performance Index $($SPI$)$ is calculated by$...$

Question $4$ options:

dividing Earned Value $($EV$)$ by Actual Cost $($AC$)$

dividing Planned Value $($PV$)$ by Actual Cost $($AC$)$

dividing Planned Value $($PV$)$ by Earned Value $($EV$)$

dividing Earned Value $($EV$)$ by Planned Value $($PV$)$